I can tell you that my ancient dual-2.0 (why, it's almost a year old 😉) is virtually silent, so I can't see how the dual-1.8 would be much louder than a 1.6. If anything, the 1.8 will be quieter than the 2.0 (marginally less power consumption/heat generation, plus newer components). I mean, it might be noisier (haven't heard a 1.6), but it's very quiet.